Method and arrangement for synchronizing of printing telegraphs



1938 HJRASSOVQ, 2,140,596

METHOD AND ARIMHG'EIMEN' I I'YJR SYNCHRONIZINGV OE PRINTING TELEGRAPHSFi led Dec. 7, 1934 2 Sheets- Sheet 1 Jib sTWAss n If is 9 ATToR/vs K'srinsed as 20, 1938 U D STATES-PATENT OFF-ICE.

GEMINI. FOB

MN I SYNGHBONIZING F PRINTING TELE- amiss Horst Rassow, Berlinassignorto Siemens &

Frledenan, Germany, Hslske, Aktiengeseilschaft, Siemensstadt, nearBerlin, Germy, a corporation of Germany Application December '1, m4, No.150,390 V In Germany December 11, 1933 -or. .picture line's and aretransmitted by'corresponding impulse sequences. An object of theinvention is the provision in a facsimile telegraph system of a simple,reliable,

,and' efllcient instrumentality for eifecting syn;

chronization.

The above, and other objects of the invention are achieved by theprovision of a facsimile receiver arranged with a power-driven spiralprints i5 'ing edge which carries a stop 'arm arranged to be nsaged oncefor each revolution by a stop member moved in the path of the stop armunder the control of a signal-responsive-magnet which is deenergizedintermediate eachseries-of symbol- 1 go representing impulses and whichis reenergized from the transmitter at the beginning of the next seriesof symbol-representing impulses'for h allowing an'additional cycle ofthe printing edge.

' Synchronizationof the apparatus is accordingly accomplished. in vReference isto be had tothe accompanying drawings, in which Fig. 1' is adiagrammatic view showing how, for transmission purposes, the letter --Uis'v-analyzed or scanned according to a system in which the field issubdivided into. twelve par allelstrips' or lines; Fig. la is a faceview of a cam disc controlling the transmission of said letter'; Fig, 2is a perspective view showing a portion oi.' the transmitter; Fig. 3 isa perspective view 5 showing a portion of the receiver; Figs. 1, 1a, 2,

and 3-are merely illustrative of the type of printing telegraph to whichmy invention relates; Fig.

4 is a plan view, and Fig. 5 is a side elevation, of

a printing telegraph receiver embodying my in- 40 vention.

I .Fig. 1

Fig. 1a shows a. disk 3 with portions 2 forming cams-located at a;greater distance from the center than the intervening portions 2', theseveral' portions 2, 2 being of proper circumferential extent to operatea suitable circuit-closer.

' upon rotation of the cam disk, in such a manner that the periods ofcurrent impulses and oi interruptions will correspond respectively tothe black and the white portions or the letter U shown in Fig. 1. Theshortest cam disk portions or intervals 2, 2' (current or no currentrespectively) occupy xiooth vof the length of the circumference of thecam disc 3 which serves to transmit. the

shows how for instance the letter U is analyzed with the aid of twelveindividual lines l.

' Thccams 5 differ as to the arrangement of their (cans-sat) letter andthe necessary space. After the transmission of the signal impulsesrequired to transmit the particular letter there follows a no-currentinterval of at least %th of the circumference ofthe disc.

' Fig. 2 shows a diagrammatic representation of a keyboard sender. On ashaft 4 which makes five revolutions per second, are arranged 48 camdiscs I for the transmission of figures and letters. teeth 6, sucharrangement corresponding to the 10 picture analysis ota letter, figure,or other Si n.

. The .problem now to be solved is to couple the keyboard 01' the senderto these discs so that at every revolution, only the picture signalofone letter is eflective. To attain this a keyboard lock must be arrangedso that when a key is operated, the remaining keys are locked. Only,during the quarter revolution, "while the space between two letters isbeing transmitted, are the keys unlocked. If, in this time interval, thekey L, for e I ple,is operated-an insulated distance-piece 'l' ited tosuch 'a position that the contact springs ad.- iaoent thereto are openedand closed-in accordance with the cams on the disc corresponding to theletter L. All other contact springs remain in the open condition, sincetheir. distance pieces are in the normal position under the action ofthekey lever springs-2.

The signals are sent by' audible frequency alternating current so thatthey may easily be transmitted over any keying lines to the radiotransmitter and on the other hand, to take advantage of the telephonelinks generally employed. The carrier frequency is 900 cycles. I,

The principle of operation of the receiver is shown in Fig. 3.

The essential part of the receiver is a printing spiral formed on asmall roller running at revolutions per second. Contact between theprinting spiral 8 and the paper band or tape 9, at a speed-of fiveletters per second, occurs twelve times from the top to the bottom andprints a line. In order to obtain immediate, visible, impression on thepaper, this is covered with a thin carbon paper of the same width, whichfor clarity is omitted from the diagram. If the receiver is energized bya current, the receiving magnet it.

attracts its armature II. This presses a rounded edge or platen l2 fromunderneath and against the paper tape I so that a line is recorded ifthe magnet l0 remains energized for the entire duration of thetransmission ofa line. At the next revolution the paper tape is steppediorward by the paper feed device it so that the next occurs close to thefirst.

,In Fig. 3 the printing spiral I is duplicated on therolier so that theletter picture is recorded simultaneously in two parallel lines. Thepurpose 01' this double record is to secure a synchronizing arrangement.The lines of print are accurately parallel only if the number ofrevolutions of the print spiral 8 is in exact accordance with thetransmission time of the picture lines. It these speeds difler from oneanother the length of the ceiver after each line, corresponding to thescanpicture lines are not parallel to the paper strip but run upwards ordownwards.

The above described well-known telegraph apparatus obviates errors dueto an inaccurate phase relationship of the transmitter and thereceiver,by producing a double record of the letters in two parallel lines,sothat at least one of the duplicate letters is recorded readably. Butthis particular in wireless transmissions.

In accordance with the invention thesedisadvantages are overcome by anarrangement which in accordance with transmitted synchronizationimpulses momentarily checks, that is, arrests or brakes the rotatingprinting member or wheel after the recording oi each line, in which thereceived letters, or other symbols are analyzed.

The rotating transmitter device includes means to transmitsynchronization impulses for momentarily arresting the printing memberon the rening of the letters or other symbols. It is useful by the factthat the stopping of the printing member is efl'ected by a spacingsignal after each line corresponding to a scanning oil the lettersignals, because in wireless transmission the adjustment can not beeflected by a marking signal, since static can effect a stopping of theprinting member. I

It is also necessary that the adjustment of the phase relationship becontrolled by a spacing signal in continuation of a marking signal.

It is advantageous to efl'ect the stopping of the printing memberelectrically or mechanically by the receiving magnet system for thedirect adjustment by the receiving magnet system. a stop being arrangedon the armature of receiving magnet system to arrest the printingmember. It is also possible to effect the stopping by a circuit forregulating the driving motor oi? the member.

printing member which is controlled by a contact of the armature oi thereceiving magnet system and a second contact which-is closedindependently of the phase relationships 01' the printing In Figs. 4 and5 of the accompanying drawings the invention is' illustrated in oneexample of construction. 7

The motor 1 of the receiver runs a little faster than the transmitterand drives by the friction clutch 2 the printing member 3. Underneaththe printing member 3 is arranged a carbon paper 5 and the paper tape 4,which are pressed against the printing member by the edge 6 of thespringretracted armature I when the magnet 8 is ener-.

gized. The recording of the letters, figures and other symbolsiseiiected in the same manner as described and shown in Fig. v3 by theco-operation oi. the platen-forming edge 6 of the armature with theprinting member. Every letter is analyzed in lines which are nearlyperpendicular to the direction of the movement of the recordingpaper. Onthe printing member 3 is arranged a stop 9, which after the scanning ofone line, in

this case, after one revolution of the printing member, comes against alatch I 0 on the armature of the receiving magnet and the printingmember is thus stopped. By a subsequent impulse the armature l isattracted, thus releasing the printing member for another revolution.

The paper feed is eflected continuously by the rollers i I and i2.

I claim: 1. In a printing telegraph apparatus, a transmitter havingmeans to send a series of electrical signal impulses constitutingelements which collectively represent a scanning line of a symbol I andto transmit synchronizing impulses intermediate successive series ofline-representing impulses which are elements in the transmission of thesame symbol, in combination with a receiver having a rotary printing andsynchronizing mem' her, and a single signal-responsive member responsiveto all of said printing and said synchronizing impulses and cooperatingwith said rotary printing and synchronizing member to print or tosynchronize alternatively.

2. In a facsimile receiver, a single-line rotary printing membereffecting printing of a single scanning line at each revolution, astart-stop element on said rotary printing member, a signalresponsiveprinting member, a further start-stop element on said signal-responsiveprinting element, said start-stop member and said further start-stopelement engageable together at each revolution of said rotary printingmember in response to a received synchronizing signal to stop saidrotary printing member after effecting printing of eachscanning line forsynchronizing.

HORST RASSOW.

